The present invention relates to devices and methods for measuring properties of materials in fluids, and particularly to determining the density of materials in pneumatic or hydraulic conveying systems.
Due to cost-effectiveness, speed and ease of application, and thoroughness of coverage in both open and confined areas, the practice of using pneumatically delivered (e.g., blown or sprayed) fibrous insulation materials, such as fiberglass, is a popular method for installing insulation in new and existing buildings. Components of a typical blown delivery system include a source of insulation material, conduit means (e.g., ducts) for conveying the insulation material from the source to the installation site, and a source of pressurized air such as a compressor, blower or the like, for generating a flow of pressurized air for entraining the insulation material and delivering it from the source through the conduit means for discharge at the installation site.
Typically, the insulation material used in conventional insulation spraying and blowing machines is packed in bags, or is baled, for shipment to the user. Upon being opened, these bags or bales are emptied into the receiving hopper of a conventional insulation spraying and blowing machine. The insulation material in the hopper is then dispensed by the system.
Of particular interest is monitoring and determining the amount of insulation material dispensed by the system. One previous technique for monitoring and determining the amount of material dispensed by the system includes counting the number of bags or bales that have been emptied into the hopper. A disadvantage of this technique is that the bag or bale size is often not commensurate with the amount of insulation material required. For example, a particular application may require 10.2 bales of insulation material. It is difficult to determine that {fraction (2/10)} of a bale has been dispensed by visually inspecting the hopper.
Another technique involves measuring the amount of insulation material delivered at the installation site. This technique is often impracticable because access to the installation site is limited or non-existent. For example, it is not practicable to measure the delivered amount of insulation material inside a wall of a building.
A further disadvantage of the above-described techniques is that the amount of insulation material dispensed is not determined in a manner timely enough to allow controlling the pneumatic conveying system (e.g., turn system off when required amount of material has been delivered). Thus, a need exists for a more accurate technique for monitoring and determining the amount of material being dispensed by the system. Further, a need exists for an in situ, real time, dynamic, system and technique for measuring airborne material in a pneumatic conveying system.
A device for measuring, in situ, the density of a material flowing in a duct includes a duct segment in fluid communication with a conveying system. The weight of the duct segment is measured independent of the weight of adjacent portions of the conveying system.
Advantages of a device in accordance with the present invention include real time measurement of material flow, weight and delivery amount; accurate measurement of material flow, weight, and delivery amount; and real time control of the delivery system. A further advantage of a device in accordance with the present invention is the ability to monitor material delivery amount in situations which are otherwise impracticable (e.g., measured the amount of delivered amount of insulation material inside a wall).
Further, a method for measuring, in situ, the density of a material flowing in a duct includes weighing a duct segment having material free fluid flowing therein to obtain a first weight. The duct segment having a mixture of material and fluid flowing therein is also weighed to obtain a second weight. The first weight is subtracted from the second weight to determine the weight of the material. The weight of the material is divided by the length of the duct segment to determine, in situ, the linear density of the material in the duct segment.